ok you can try this steps but you might loose some data.
REboot in DOS. you can eaither try:
1. start-->shut down--> and select restart in ms-dos
or
2. with the windows recovery floppy disk select minimal boot.
Once you are in DOS. Type scanreg /restore and hit enter.
You will see some dates. select the date before you install the office XP.
ps. Before you try this make sure that you unplug all objects from PC like printer, scanner. Just leave the keyboard, mouse and speaker if they came with it.